Vassia is a female Greek name deriving from name Vassiliki. Vassia is not a very common name, but it’s one of the typical nicknames and diminutives of the name Vassiliki. Vassia in Greece is just a female name, opposite from Slavic languages where Vassia is a male name.
Male Version of name Vassia: Vassilis
Nameday of name Vassia: January 1st
Origin of name Vassia
Since Vassia is a name deriving from the main name Vassiliki, it also refers to Agios Vassilis (St Basil). You can find more details for Agios Vassilis, at the pertinent post for name Vassilis.